1. Field of the Invention
The invention relates to an indicating instrument and a casing therefor.
2. Description of the Prior Art
Indicating instruments are already known in which the casing of plastic material forms a one-piece unit with the front frame. Such indicating instruments have the disadvantage that wishes of the buyer regarding the style or design of the front frame as to shape and/or dimension can only be realized, if at all, by a costly alteration of the extrusion die.
Furthermore, it has been proposed to construct the front ring of the indicating instrument so as to be capable of being slipped or screwed onto the casing. Such a structure permits the attachment of a great variety of front rings to the casing without having to make alterations to the extrusion die for the casing. This solution, however, is not transferable to front frames, which frequently are of a non-circular shape, since front frames, due to their size and their weight, usually cannot be slipped on but must be capable of being screwed on.
Therefore, substantial difficulties arise in the correct positioning of the frame with regard to fixing on the casing.